Radio-frequency power divider circuit



y 2 G. L. RAGAN 2,605,356

RADIO-FREQUENCY POWER DIVIDER CIRCUIT Filed May 9, 1945 2 SHEETSISHEET 1 FIG. I

LOAD

: 4| l l 0 MC 2a [4 4 E 2 44 42 46 43 45 FIG-.3 H L 41 ND RECEIVER INVEN TOR GEORGE L. RAGAN ATTOR EY y 1952 G. L. RAGAN FREQUENCY POWER DIVIDER CIRCUIT RADIO- Filed May 9, 1945 2 SHEETSSHEET 2 FIG. 4

F IG. 5

MAXIMUM PLUNGER TRAVEL INVENTOR. GEORGE L. RAGAN AT TORNEY Patented July 29, 1952 RADIO-FREQUENCY POWER DIVIDER CIRCUIT George L. Hagan, Cambridge, Mass., assignor, by mesne assignments, to the United States of America. as represented by the Secretary of the Navy Application May 9, 1945, Serial No. 592,798

20 Claims.

This invention relates to a radio frequency power divider circuit and particularly to a means for dividing in any suitable proportion the radio frequency output to two or more parallel transmission lines.

In radio frequency technique and especially in the ultra high frequency spectrum, it often becomes desirable to proportion the power output to two or more transmission lines and to provide a suitable means for varying this proportionality at will. For example, such a means is utilized in the application of Luis W. Alvarez entitled, Radio Echo Locator Systems for Approaching Hostile Craft, Ser. No. 514,404, filed December 15, 1943, now Patent No. 2,530,418, issued November 21, 1950. In this patent there is disclosed a pair of parallel transmission lines, one having a dummy load fixed thereto and the other a directional antenna with a means of the type described hereinafter for automatically regulating the output power ratio from the parallel transmission lines.

It is therefore an object of this invention to provide a means for dividing in any suitable proportion the radio frequency power output to two or more transmission lines. i

It is another object of this invention to provide a means for dividing in any suitable proportion the radio frequency power output to'two or more transmission lines and having incorporated therewith ,a means for regulating said proportion at will.

It is another object of this invention to provide a transmission line construction having an input line, and two or more parallel output lines joined thereto with a means for dividing inany suitable proportion the power output from each of said parallel output lines without disturbing the effective terminating impedance of said input lines.

It in another object of this invention to provide a power divider circuit which will produce one division of the power when relatively large amounts are applied thereto and another division upon the application of relatively small amounts of power.

Other objects and features of the present invention will become apparent upon a carefulconsideration of the following detailed description when taken together with the accompanying drawings, the figures of which illustrate typical embodiments of the invention.

Fig. 1 is an elevational view in cross section of a preferred embodiment of the present invention.

Fig. 2 is a cross sectional view of a modification of Fig. 1.

Fig. 3 is an elevational view in cross section of a second modification of Fig. l.

Fig. 4 is an elevational view in cross section of a third modification of Fig. 1.

Fig. 5 is a power divider power diagram.

Fig. 6 is a partial detail section along line 6-6 of Fig. 1 with the tube removed.

Reference is had more particularly to Fig. 1 wherein there is shown a preferred embodiment of the present invention. The apparatus shown herein includes two stub sections of transmission lines 20 and 2| situated on each side of a T-junction 22 formed by an input line 23 joined to a pair of output lines 24. The stub sections are separated from the T-junction by an odd multiple of electrical quarter wave lengths, preferably one, and are terminated by a pair of respective radio frequency shorting plungers 25 and 26 which will be described more fully hereinafter. Plungers 25 and 26 are adapted to be moved simultaneously and in such a manner that a constant difference of one quarter wave length will be maintained in their respective lengths of stub sections. That is, for example, in one position of plunger 25, stub section 20 measured from the plunger to the joint it makes with line 24 may be an electrical half wave length, while the corresponding position of plunger 26 will render stub section 2|, measured from thesame limits, one quarter wave length long. Plungers 25 and 26 are actuated by rods 21 and 2t mounted on a suitable frame-or yoke, illustrated schematically in Fig. 1 by the dashed line 28'. A suitable load such as 29 and 30 may now be applied to each end of the transmission line 24 and matched with the characteristic impedance thereof in order to avoid standing waves. 7

. When it becomes desired to divert practically all the power from line 23 to load 30, plungers 25 and 26 are moved simultaneously to a point where plunger 26 renders stub section 2!. equal to an electrical quarter wave length thereby presenting a high impedance at the stub sections jointto line 24, and therefore, will not interfere with the transmission of energy to load 38. At this setting of the plungers, plunger 25 renders stub section 2!] .an electrical half wave length in length (due to the previously discussed relative position of the plungers) to short circuit transmission line 24 at the stub section 20 joint and thereby present a high impedance at the T -junction since stub section 20 is located an electrical quarter-wave length from the T-ju'nction.

It may be desired to'distribute the power from line 23 in some predetermined proportion to both loads-29 and 30. This may be accomplished by simultaneously lengthening the stub sections 28 and 2|. It will be'noted that such simultaneous lengthenings of these stub sections will not set up any substantial amount of standing waves in line 23, but will preserve the desired condition of impedance matching because the susceptance presented at the T-junction 22 by an increase in length of section 2| will be balanced by an equal or opposite susceptance presented at the same point by a corresponding increase in length of section 20. At the same time the sum of the two conductances presented at the T-junction 22 remains equal to the characteristic admittance of line 23. This results from the fact that the distances from the ,T-junction 22 to the plungers 25 and 26 differ by an odd multiple of electrical quarter wave lengths. If desired; power may be distributed in some predetermined proportion by advancing rather than retracting the plungers 25 and 26.

The plungers 25 and 26 which are adapted to perform a short circuitingiunction are so deternal sleeves 39 and' lll. The sleeves 31, 38, 39,

and 40 are slightly less than a physical quarter wave length long so'tha't the clearance space external of the external sleeves 37 and 38 is adapted to constitute a transmission line of one electrical quarter wave length, and likewise the clearance space located internally of the internal sleeves 33 and 40. The axial dimension of thecavities between sleeves 31, 32, and sleeves 3'! and 38 and between sleeves'3 I, 32, and sleeves 39 and 49 will also have an electrical length equal to one quarter wave length. In consequence; a very low impedance 'for the radio frequency in use here is provided at the external head surfaces of plungers 25 and 26 and the respective conductors of the stub section 20 and 2i. The operation of plungers of this type is more fully described in the patent application of W. W. Salisbury, Ser. No. 478.793, filed March 11, 1943, now Patent No. 2,541,836, issued February 13,1951.

This divider may be used in the antenna feed of a transmitter: Here load 29 may be an antenna and load 33 a dummy. The line 23 may be connected'to the output of the transmitter. By varying simultaneously the position of the plungers the output to the antenna load may be reduced from maximum as desired. In a radar system the reflected pulses are ordinarily received by the same antenna as that used in transmitting. When the divider is used in connection with a radar system the reflected pulses will be received by the antenna at 29 and transmitted to a receiver connected to the input 23. The divider will attenuate the received signal the same amount proportionally as the transmitted signal. To partially overcome this undesired attenuation a gas switch device 19 may be placed in series with stub section 20, one half wave length away from the junction I! of this stub section with line 24. The gas switch device may be, for example, an anti-TR. box. Such an anti-TR box may be in the form of a cavity resonator having conductive into load '55.

amplitude will excite the cavity without causin an arc discharge between the inwardly extending cones. On the other hand, high amplitude signals will create an arc discharge between the tWo cones which places a low impedance shunt between the opposite walls of the resonator. The switch device I9 will be broken down by a transmitted signal to provide a zero impedance series circuit at the junction l8 of the stub section 29. Hence the switch is efiectively not in the circuit when the transmitter pulse passes down the line, so the attenuation is that of a simple divider.

I When there is no transmitted signal the switch device will be resonant and efiectively an open circuit will occur at junction 18 of stub section 20. This reflects an open circuit in shunt with line 24 at junction 11, and stub section is rendered ineifective. Hence a received signal will pass junction I! without attenuation there. If the plunger 25, when positioned a half wave length from junction I7, interferes with the operation of the switch device, which is also spaced a half wave length from junction 11, plungers 25 and 25 may be moved outwardly from line 24 one half wave length and will operate in this newposition substantially as well.

If desired, the form of the powerdivider circuit shown in Fig. 1 may be modified by interchanging the position of the output legs and the stub section as shown in Fig. 2. 'In Fig. 2 the input line is shown at =4! and the output lines are shown at and 41. The stub sections are likewise interchanged and shown at 42 and 43 terminated by the respective plungers 4-4 and 45. In this form the plungers M and are to be moved in opposite directions during the power dividing operation instead of in-the same direction with the distance of plunger 55 from line '4'! always exceeding the distance of plunger 44 from line '46 by an electrical quarter wave length, since the stub sections extend outward at right angles from the input line GI and not parallel therewith. Thus plunger 44 will have to be moved to the left while plunger 45 is simultaneously moved to the right which will involve a more complex mechanism for actuating the plungers than heretofore discussed.

Another form of power divider is shown in Fig. 3 where a wave guide transmission line is used in place of the coaxial transmission line of Fig. 1. This power divider is made by placing in series with line branch lines 52 and 53 with branch 5| therebetween. A source of power is connected to branch5l. The purpose of the powerdivider is as in the other modifications to divide the power between loads 5:1 and 55in any desired ratio. Branches 52 and 53.have shorting plungers 56 and 5-l, respectively. These plungers are ganged to'move together, and are spaced axially one quarter wave length apart along branch lines 52 and 53. The yoke or frame for moving plungers 55 and-Elfis diagrammaticallyillustrated by dashed line 58 in Fig.3. 1

If the plungersare moved so that plunger'5'l is effectively one quarter wave length from the junction of stub 53 with line-'50, allthe power goes into load 5G. With plunger '51 one half wavelength from the junctiom all the power goes For any ratio ofv powerdivision desired between these two extremes there is a corresponding setting of the plungers in between the positions mentioned above. Furthermore, if loads 54 and 55 are both matched to lineimpedance, then looking into the divider from branch 5| amatched load is seen for, all settings of the -plungers.

, To usethisdevice as an attenuator between the transmitting tube and the antenna,,load 55 may be a dummy and load 54 an antenna properl matched to line 50, while the power source may be connected to branch 5|. If it is desired .to receive reflected signals in a receiver, also connected to branch 5|, with less attenuation than the transmitted signals, a gas tube switching device may be used substantially similar to that in Fig. 1. This may consist of a gaseous breakdown type tube indicated generally by the numeral 60 connected in series with branch 52 and eifectivelyone quarter wave length from line 5E When-a signal is transmitted, an electric field is built up to break down tube 69 witha resulting short circuit across opening 59. Hence,

branch 52 will forma continuous circuit from plunger 53 to line 50, and the switching device will be-effectively out of the remainder of the circuit. This results in the attenuation of a simple divider.

When no signal is transmitted, the switching device, being open and being connected in series with branch 52, places an open circuit in series with branch 52 at the junction with a resulting short being reflected in series with line 50 at its junction with branch 52. Consequently, any received signal passes branch 52 without attenuation there. By using this arrangement the loss in the return signal can be cut from 35 db at a maximum attenuation to less than 5 db. At minimum attenuation position, the switch has no eiiect.

The principles of this invention are readily applicable, where it is desired to distribute power to more than two loads from a common source. The embodiment in Fig. 4 performs this function. Here a common source ll] feeds three outputs 8!], SI, and 82 through the instant embodiment. Quarter wave stubs ll, 12, and i3 are used to support the internal conductor of the coaxial cable. Short-circuiting plungers 85, 8G, and 81 may be adjusted to distribute the power between the outputs 8G, 8! and 82. Any one of the three plungers (e. g. plunger 85') may beset to an electrical half wave length from the junction with the associated load (e. g. output 80) thus shorting this load and reflecting an open circuit in parallel with the input line at 79. The remaining two plungers (e. g. plungers 86 and 81) may then be moved as a unit with a fixed separation of a quarter wave length. The power is then divided between the associated outputs (e. g. 81 and 82) in the manner described above in connection with Fig. 1, and no substantial amount of standing waves will be introduced into the line at 70. Any two of the plungers may be so moved as a ganged unit, with the third placed in the half wave length position.

The number of loads, associated stubs, plungers, etc.,may be iterated at half wave length intervals along the line at 70. In this case, any two plungers may be moved as a ganged pair to divide the power between the associated loads in whatever ratio is desired. All plungers other than these two should be set at the half wave length position.

,,In the chart of Fig. 5 the power division between a pair of loads over a quarter wave length of plunger travel is represented. Applying this chart to the form in Fig. 1 curves A and B may represent the power drawn by loads 29 and 30, respectively, and the origin 0 representsthe' po- 6 sition of the plungers, when plunger 26 is spaced a quarter wave length from the line 24. Fig; 6 illustrates the details of connecting the anti-TR cavity to the line. It is here seen that coinciding slots are provided in the outer conductor of branch 20 and in'the TR cavity to form an opening l6.

In order to avoid undesired coupling from stray field that may arise in the neighborhood of the switching arrangement, quarter wave choke cups may be mounted on the outside of transmission lines Hand 24 adjacent the divider. These prevent transmission of" radio-frequency current along the outside of these transmission lines. These may also be applied to the wave guide counterparts in the modification in Fig. 3. It

. is further to be understood in connection with the power divider apparatus that wherever the electrical lengths of a quarter or half wave length are specified, an odd multiple or an even multiple, respectively, of a quarter wave length may be used equally as Well. Likewise, where the term electrical length is used, it is to be understood as meaning av physical length of such value as to give the electrical effect of the corresponding electrical length in free space. Thus, the electrical lengths mentioned are to be taken as including the contribution of "end effects. All distances referred to in terms of wave lengths are to be electrical lengths as defined above.

Although I have shown and described only certain and specific embodiments of my invention, I am fully aware of the many modifications possible thereof. Therefore, this invention is not to be limited except insofar as is necessitated by the prior art and the spirit of the appended claims.

I claim: 9

1. A radio frequency power divider circuit, comprising an input coaxial transmission line having inner and. outer conductors, a pair of output'coaxial transmission lines each also having inner and outer conductors joined to the respective conductors of said input transmission line so as to form a T-junction, a pair of coaxial line stub sections, each of said sections joined to a respective one of said output lines at a point an integra1 number of odd quarter Wave lengths from said junction, and means for shorting the conductors of each of said stub sections at points that difier between respective stub sections by any odd multiple of quarter wave lengths, the length of said stub sections measured from said output line to said shorting means being adjustable and means for simultaneously varying the position of said shorting means on both of said stub sections.

2. A radio frequency power divider circuit, comprising an input coaxial transmission line having inner and outer conductors, a pair of output coaxial transmissionlines each also having inner and outer conductors, a coaxial conductor link joining said output lines in parallel at points separated by any odd integral number of one-half wave lengths, said conductor line extending outward from each output line junction by at least one-half Wave length, means connecting said input line to the midpoint of said conductor link between said output lines, means for shorting the conductors of said conductor link at opposite ends and at points that differ in length from the respective output line junction by any odd integral of one quarter wave lengths, and means for simultaneously varying the'position of said shorting means.

3, A radio frequency power divider circuit, comprising an input coaxial transmission line having inner and outer conductors, a pair of output coaxial transmission lines also having winner and outer conductors, a coaxial conductor conductor link,

(i. A radio frequency power divider circuit, comprising an input wave guide, a pair ofoutput guides connected to said input guide ata commonpoint, to form an electrical T-junction, a branch guide with an associatedmovable shorting plunger connected .in series to each of said output guides at a distance of a quarter wave length from said T-junction, the effective electrical length of one of said branch guides being a quarter wave greaterthan the other, whereby the power from said input guide may be divided in the desired proportion in said output guide in response to movement of said plungers, while maintaining the impedance presented to said inputline at said T-junction substantially unchanged. a ,r

5. A radio frequency power divider circuit, comprising an input coaxial line adapted to be connected to a radar transmitter and receiver, a pair of output coaxial lines respectively adapted to be connected to an antenna and a dummy load, andconnectediat a common point to said input'line to form, a T-junction, a-branch line with an associated movable shorting plunger connected to each of said output lines .at a distance of quarter wave length from said T- junction, the effective electrical length of one of said branch linesbeing a quarter wave length greater than thev other, a gas tube connected in series with the antenna branch line and at a distance of a half wave length from the antenna outputline, said gas tube being adapted to break down when thetransmitter signal is applied and thereby render effective the antenna branch line to divide the transmitter power between the antenna and dummy in accordance with the position of the branch line plungers and being further adapted in the absence of the transmitter signal to remain open and thereby render ineffective the antenna branch line, whereby a received signal will not be attenuated by said antenna branch line. 7

6. A radio frequency power divider circuit, comprising an input wave guide adapted to be connected to a radar transmitter and receiver, a pair of output wave guides respectively adapted to be connected to an antenna and a dummy load and connected at a common point to said input guide to form a T-junction, a branch guide with an associated movable shorting plunger connected to each of said output guides, at a distance of a quarter wave length from said T- junction, the effective electrical length of one of said branch guides being a quarter wave length greater than the pother a gas tube connected in series with the'antenna branchguide and at a distancerof' a quarter wave length from the antenna output guide, said gas tube being adapted to breakdown when the transmitter signal is applied and thereby render eifective the an tenna branch guide to divide the power between the antenna and dummy in accordance with the position of the branch guide plungers, and being further adapted in the absence of the transmitter signal to remain open and thereby render ineffective the antenna branch guide, whereby a received signal will not be attenuated by said antenna branch guide.

'7. .A radio frequency power divider circuit, comprising an input line, a first output line, a branchlin'e connecting said input and said first output lines and of a length equal to an odd integral number of quarter wave lengths, a second output line, a second branch connecting said input and second output lines and of a length equal to an odd integral number of quarter wave lengths, a third. output line, a third branch connecting said third output line to said second branch at an odd integral number of quarter wave lengths from said second output and of a length equal to an odd integral number of quarter wave length, a stub line with adjustable shorting plunger connected at the junction of each output line and its associated branch, and means arranged simultaneously to adjust the position of asclected two of said shorting plungers to maintain the effective electrical length of a corresponding one of said stub lines an odd integral number of quarter wave lengths greater than the effective electrical length of the other corresponding stub line.

8; A radio frequency power divider circuit, comprising an input line, a plurality of branch lines spaced a half wave length apart upon said input line, an output line connected to each of said branch lines and at a distance of a quarter wave lengthfrom the junction of said input line and the respective branch line, a movable shorting plunger in each of said branch lines, any two of said plungers being ganged with the effective electrical length of the associated-branches difiering byian odd integral number of quarter wave lengths, whereby theinput power may be proportioned between the output lines associated with said ganged plungers.

9. A radio frequency power divider circuit, comprising an input enclosed transmission line adapted to be connected to a radar transmitter and receiver, a pair of output enclosed transmission lines respectively adapted to be connected to, an antenna and a dummy load and connected at 'a common point to said input line to form a T-junction, a branch line with an associated movable shorting plunger connected to each of said output lines at a distance of a quarter wave length from said T-junction, the effective electrical length of one of said branch lines being a quarter wave length greater than the other, a gas tube connected in series with the antenna branch line and at a distance of a half wave length from the antenna output line, said gas tube being adapted to break down when the transmitter signal is applied and thereby render effective the antenna branch line to divide the transmitter power between the antenna and dummy load in accordance with the position of the branch line plungers and being further adapted in the absence of the transmitter signal to remain open and thereby render ineffective the antenna branch line, whereby a received signal will not be attenuated by said antenna branch line.

10. A radio frequency power divider circuit,

comprising an input enclosed transmission line;

and at a distance of a-half wave length from the' first terminal means output line, said gas tube being adapted 'to break down when a high intensity signal is applied to said input line and thereby render effective" the first terminal means branchline to divide the high intensity signal between the first terminal means and the second terminal means in accordance with the position of the branch line plungers and being further adapted inthe absence ofthe high intensity signal to remain open and thereby render ineffective the first terminal means branch line, whereby a signal from said first terminal means will not be attenuated by said first terminal means branch line.

11. A radio frequency power divider circuit, comprising an input coaxial line, a pair of output coaxial lines respectively-adapted to be connected to a first and second terminal means and connecte at a common point to said input line to form a T-jun'ction, a branch line with an associated movable-shorting plunger connected to each of said output lines at a distance of a quarter wave length from said T-junction, the effective electrical length of one of said branch lines being a quarter wave length greater than the other, a gas tube connected in series with the first terminal means branch line and at a distance of a half wave length from the first terminal means output line, said gas tube being adapted to break down when a high intensity signal is applied to said input line and thereby'render effective the first terminal means branch line to divide the high intensity signal between the first terminal means and the second terminal means in accordance with the position of the branch line plungers and being further adapted in the absence of the high intensity signal to remain open and thereby render ineffective the first terminal means branch line, whereby a signal from said first terminal means will not be attenuated by said first terminal means branch line.

12. A radio frequency power divider circuit, comprising an input wave guide, a pair of output wave guides respectively adapted to be connected to a first and second terminal means and connected-at a common point to said input wave guide to form a T-.junction, a branch line with an associated movable shorting plunger connected to each of said output wave guides in a series junction at a distance of a quarter wave length from said T-junction; the effective electrical length of one of said branch lines being a quarter wave length greater than the other, a gas tube connected in series with the first terminal means branch line and at a distance of a quarter wave length from the first terminal means output wave guide, said gas tube being adapted to break down when a high intensity signal is applied to said input wave guide and thereby render effective the first terminal means branch line to divide the high intensity signal between the first terminal means and the second terminal means in accordance with the positionof the branch line plungers and being further adapted in the absence of the high intensity signal to remain open and thereby render inefiective the first terminal means branch line, whereby a signal from said first terminal means will not be attenuated by said first terminal means branch line.

13. A radio frequency power divider circuit as in claim 10 said divider circuitfurther comprising means for simultaneously varying the position of said branch line plungers, said last-mentioned means maintaining said quarter wave length difference in effective electrical length.

14. A radio frequency power divider circuit comprising an input enclosed transmission line, a pair of outputenclosed transmission lines respectively adapted to be connected to a first and second terminal means and connected at a common point to said inputline to form a T-junction, a branch line with an associated movable plunger connected to eachof said output lines at a distance of any odd number of quarter wave lengths from said T-junction, said odd number including the number one, the efiective electrical length of one of said branch lines being any odd number of quarter wave lengths greater than the other, said last-mentioned odd number including the number one, electrical breakdown means connected in series with the first terminal means branch line and at a distance of an integral number of half wave lengths from the first terminal means output line, said electrical breakdown device being adapted to break down when a high intensity signal is applied to said input line and thereby render efiective the first terminal means branch line to divide the high intensity signal between the first terminal means and the second terminal means in accordance with the position of the branch line plungers and being further adapted in the absence of the high intensity signal to remain open and thereby render ineffective the first terminal means branch line, whereby a signal from said first terminal means will not be attenuated by said first terminal means branch line, I

15. A radio frequency power divider circuit as in claim 14 further comprising means for simul taneously varying the position of said branch line plungers, said last-mentioned means maintaining said difference in effective electrical length.

16. A radio frequency power divider circuit comprising an input enclosed transmission line, first and second outputenclosed transmission lines connected to said input transmission line at a common point to form a T-junction, first and second branch lines respectively connected to said first and second output transmission lines at a distance of any odd number of quarter wave lengths from said T-junction, means for adjusting the effective electrical length of said branch lines, the eifectiveelectrical length of one of said branch linesv being any odd number of quarter wave lengths greater .than the eifective electrical length of the other branch line, electrical switch means connected in series with said first branch line, said electrical switch means presenting a relatively low series impedance to high intensity signals and relativel high impedance to low intensity signals, said electrical switch means being spaced an integral number of quarter Wave lengths from the junction Of said first branch line and said first output line, said last-mentioned integral number being such that for low intensity signals said first output line is effec- 11" tively electrically continuous and unshunted at its junction with said first branch line whereby signals of relatively high and relatively low intensity-may be differently divided.

17. A radio frequency, power divider circuit comprising an input'enclosed transmission line, first and second output enclosed transmission lines'connected to said input transmission line ata common point to form a T-junction, first and second branch lines respectively connected to said first and second output transmission lines at a distance of an odd number of quarter wave lengths from said T-junction, means for adjusting the effective electrical length of said branch lines, the effective electrical length of one of said branch lines being any-odd number of quarter Wave lengths greater than the effective electrical length of the other branch line, electrical switch means coupled to said first branch line, said electrical switch means terminating said first branch line in a high impedance at its point of connection thereto for relatively low intensity signals, said switch means causing said first branch line to be substantially electrically continuous and unshuntedat its point of connection thereto for relatively high intensit signals, said point of connection of said switch means being spaced an integral number of quarter wave lengths from the junction of said first branch line and said first output line, said last-mentioned integral number being such that for low intensity signals, the terminating impedance of said switch means is reflected to said last-mentioned junction to cause said first output line to be effectively electrically continuous and unshunted whereby signals of relatively high and relatively low intensity may be differently divided.

18. A radio frequency power divider circuit comprising an input enclosed transmission line, first and second output enclosed transmission lines connected to said input transmission line at a common point to form a T-junction, first and second branch lines respectively connected to said first and second output transmission lines at a distance of an odd number of quarter wave lengths from said T- junction, each of said branch lines being provided with an adjustable shorting termination, means for simultaneously adjusti-ng said shorting terminations while maintaining the effective electrical length of one of said branch lines a quarter wave length longer than the effective electrical length of the other branch line, electrical switch means coupled to said first branch line, said electrical switch means terminating said first branch line in a high impedance at its point of connection thereto for relatively low intensity signals in said first branch line, said switch means causing said first branch line to be substantially electrically continuous and of uniform impedance at its point of connection thereto for relatively high intensity signals, said point of connection of said switch means being spaced an integral number of quarter wave lengths from the junction of said first branch line and said first output line,

said last-mentioned integral number being such that for'low intensity signals, the terminating impedance is reflected to said last-mentioned junction to cause said first output line to be effectively electrically continuous and of uniform impedance whereby signals of "relatively high and relatively low intensity may be difierently divided. 7

19. A radio frequency power divider circuit comprising an input enclosed transmission line, first and second output enclosed transmission lines connected to said input transmission line at a common point to form a T-junction, first and second branch lines respectively connected to said first'and second transmission lines at a distance of an odd number of quarter wave lengths fromsai-d T-junction, each of said branch lines being provided with an adjustable shorting termination and means for simultaneously adjusting said shorting terminations while maintaining the effective electrical length of one of said branch lines aquarter wave length longer than the effective electrical length of the other branch line. I V

20. A radio frequency power divider circuit comprising,- an input enclosed transmission line, a plurality of output enclosed transmission lines respectively adapted to be connected to a corresponding plurality of terminal means, a like plurality of branch enclosed transmission lines connecting each of said output transmission lines to said input transmission line, each of said branch transmission lines having an electrical length equal to an oddintegralnumber of quarter wave lengths at the frequency of operation, a stub enclosed transmission line connected at the point of connection of each of said output transmission lines with its corresponding branch transmission line, means shorting said stub transmission lines, the length of each of said stub transmission lines as measured from its corresponding output transmission line to said shorting means being adjustable, and means arranged simultaneously to adjust the position of a selected two of said shorting means to maintain the effective electrical length of one of said two stub transmission lines an odd integral number of quarter wave lengths greater than the "eifec'tive electrical length of the other of said two stub transmission lines.

GEORGE L. RAGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,228,692 Davies Jan. 14, 1941 2,396,044 Fox Mar. 5, 1946 2,397,543 Fuchs Apr. 2, 1946 2,401,863 Espley June 11, 1946 2,404,832 Espley July 30, 1946 2,410,657 Hershberger Nov. 5, 1946 2,412,315 Brown Dec. 10, 1946 

